This invention concerns a novel and improved conveyor apparatus for conveying articles such as beverage or food cans, or other similar containers in an upright orientation, between stations in a multi-step process. The invention more particularly concerns an air conveyor with floating covers for regulating the air pressure within the conveyor apparatus.
Air conveyors have heretofore been utilized for conveying containers such as empty beverage cans between stations in a multi-step process. The cans might be conveyed for example between stations wherein the cans are initially formed to stations wherein the cans are coated in some instances with appropriate protective materials, or wherein the cans have various labels painted or otherwise applied thereupon, as well as other printed identifying marks or the like applied thereto. Finally, the cans must be conveyed to a filling operation.
These air conveyors generally comprise relatively wide, elongated elevated platforms or decks which are provided with a plurality of perforations or openings through which air is directed. Generally speaking, the perforations or openings are appropriately shaped for directing air primarily in the direction in which the cans or other containers or articles are to be conveyed. It has been found that the force of the air impinging upon the individual containers varies as a function of the number of containers which are present over a given surface area of the deck at any given time. Thus, where many containers are present, many of the openings in the deck may be blocked, causing the air to exit with somewhat greater force in the remaining unblocked openings. This increased force can in turn drive individual containers or cans at a somewhat higher velocity into preceding containers. If the force or velocity with which individual containers are propelled becomes too high, the containers may damage each other upon collision, or otherwise scrape or mar the paint or labels or other identifying information or decorative surfaces which have been applied thereto. Particularly, in the case of relatively thin-walled aluminum beverage cans and the like, some denting or deformation of the cylindrical side walls of the respective cans can occur upon collision, as the force or velocity of the individual cans increases, as well as damage to any paint finishes or surfaces which have previously been applied thereto.
Generally speaking, such creation of damaged or reject containers is to be avoided during such handling and conveying operations wherever possible, to assure that subsequent filling and handling steps can take place as expeditiously as possible, without the need for operator intervention.
The present invention specifically improves upon an air conveyor apparatus which includes a deck as described above, a top or upper surface comprising a perforated panel, and appropriate supports for maintaining the top panel spaced by a desired vertical distance from the deck. This vertical distance is generally slightly greater than the vertical height of the containers to be conveyed through the apparatus, so as to permit the containers to slide with relative ease between the deck and the top, and yet prevent the containers from tipping or tilting while being conveyed. The lateral sides of the conveyor between the lateral edges of the deck and top were heretofore provided with one or more elongated guide rails running substantially the length of the deck. The sides were otherwise left open. This was done in order to minimize the pressure buildup within the air conveyor apparatus. It was heretofore believed that any pressure buildup would only further contribute to excessive forces applied to, and velocities being attained by, the individual articles, and hence increase the incidence of damage thereto.
Surprisingly, it has been found in connection with the present invention, that a regulated amount of pressure buildup within the air conveyor apparatus may in fact have desirable rather than deleterious effects. For example, it has been found that a slightly elevated pressure tends to create an air cushion between individual articles such as cans or other containers, thus reducing the tendency of the articles to forcibly impinge on one another and cause damage. In addition, maintaining a regulated amount of pressure within the conveyor apparatus produces more of a "floating" effect, which together with the air cushion effect just mentioned tends to convey the articles more gently and avoid forceful impingement therebetween of the sort leading to the damaged articles.